An inductor, in general, is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance (symbol “L”), in units of “henries” (symbol “H”, named after American scientist Joseph Henry). Inductance results from the magnetic field forming around a current-carrying conductor, which tends to resist changes in the current. Electric current through the conductor creates a magnetic flux proportional to the current. A change in this current creates a corresponding change in magnetic flux which, in turn, by Faraday's Law generates an electromotive force (EMF) that opposes this change in current. Inductance is a measure of the amount of electromotive force generated per unit change in current. By definition, if the rate of change of current in a circuit is one ampere per second and the resulting electromotive force is one volt, then the inductance of the circuit is one henry.